1945 US air-defence technology would transform early Axis engagements

What changes if the Axis navies of 1939 receive 1945-level US fire control and sensors, together with the question's proposed proximity-fuzed 40 mm ammunition?

Early engagements become much more dangerous for Allied ships and aircraft, but the Axis still lacks the industrial base and fleet numbers to preserve the advantage through a long war.

The scenario gives Axis ships more effective fire control, sensors, and anti-aircraft weapons at the beginning of the war. It also adds proximity-fuzed 40 mm ammunition as a hypothetical capability. The Scharnhorst class is singled out as a force that could then sink Renown in an early encounter. Swordfish attacks would face much more effective defensive fire. The number of Axis ships and the infrastructure available to build replacements remain unchanged, so long-term victory remains doubtful despite these early advantages.